BACKWARD INCOMPATIBILITY: the coveragecombine command now ignores an
existing .coverage data file. It used to include that file in its
combining. This caused confusing results, and extra tox “clean” steps. If
you want the old behavior, use the new coveragecombine--append option.

Since concurrency=multiprocessing uses subprocesses, options specified on
the coverage.py command line will not be communicated down to them. Only
options in the configuration file will apply to the subprocesses.
Previously, the options didn’t apply to the subprocesses, but there was no
indication. Now it is an error to use --concurrency=multiprocessing and
other run-affecting options on the command line. This prevents
failures like those reported in issue 495.

The concurrency option can now take multiple values, to support programs
using multiprocessing and another library such as eventlet. This is only
possible in the configuration file, not from the command line. The
configuration file is the only way for sub-processes to all run with the same
options. Fixes issue 484. Thanks to Josh Williams for prototyping.

Using a concurrency setting of multiprocessing now implies
--parallel so that the main program is measured similarly to the
sub-processes.

Branch analysis has been rewritten: it used to be based on bytecode, but now
uses AST analysis. This has changed a number of things:

More code paths are now considered runnable, especially in
try/except structures. This may mean that coverage.py will
identify more code paths as uncovered. This could either raise or lower
your overall coverage number.

issue 422: in Python 3.5, an actual partial branch could be marked as
complete.

During branch coverage of single-line callables like lambdas and
generator expressions, coverage.py can now distinguish between them never
being called, or being called but not completed. Fixes issue 90,
issue 460 and issue 475.

Pragmas to disable coverage measurement can now be used on decorator lines,
and they will apply to the entire function or class being decorated. This
implements the feature requested in issue 131.

Multiprocessing support is now available on Windows. Thanks, Rodrigue
Cloutier.

The HTML report has a few changes:

The HTML report now has a map of the file along the rightmost edge of the
page, giving an overview of where the missed lines are. Thanks, Dmitry
Shishov.

The HTML report now uses different monospaced fonts, favoring Consolas over
Courier. Along the way, issue 472 about not properly handling one-space
indents was fixed. The index page also has slightly different styling, to
try to make the clickable detail pages more apparent.

The XML report now produces correct package names for modules found in
directories specified with source=. Fixes issue 465.

coverage--help and coverage--version now mention which tracer is
installed, to help diagnose problems. The docs mention which features need
the C extension. (issue 479)

The Coverage.report function had two parameters with non-None defaults,
which have been changed. show_missing used to default to True, but now
defaults to None. If you had been calling Coverage.report without
specifying show_missing, you’ll need to explicitly set it to True to keep
the same behavior. skip_covered used to default to False. It is now None,
which doesn’t change the behavior. This fixes issue 485.

It’s never been possible to pass a namespace module to one of the analysis
functions, but now at least we raise a more specific error message, rather
than getting confused. (issue 456)

The coverage.process_startup function now returns the Coverage instance
it creates, as suggested in issue 481.

When combining data files, unreadable files will now generate a warning
instead of failing the command. This is more in line with the older
coverage.py v3.7.1 behavior, which silently ignored unreadable files.
Prompted by issue 418.

The –skip-covered option would skip reporting on 100% covered files, but
also skipped them when calculating total coverage. This was wrong, it should
only remove lines from the report, not change the final answer. This is now
fixed, closing issue 423.

In 4.0, the data file recorded a summary of the system on which it was run.
Combined data files would keep all of those summaries. This could lead to
enormous data files consisting of mostly repetitive useless information. That
summary is now gone, fixing issue 415. If you want summary information,
get in touch, and we’ll figure out a better way to do it.

Test suites that mocked os.path.exists would experience strange failures, due
to coverage.py using their mock inadvertently. This is now fixed, closing
issue 416.

Importing a __init__ module explicitly would lead to an error:
AttributeError:'module'objecthasnoattribute'__path__', as reported
in issue 410. This is now fixed.

Code that uses sys.settrace(sys.gettrace()) used to incur a more than 2x
speed penalty. Now there’s no penalty at all. Fixes issue 397.

Pyexpat C code will no longer be recorded as a source file, fixing
issue 419.

The source kit now contains all of the files needed to have a complete source
tree, re-fixing issue 137 and closing issue 281.

Coverage.py is now licensed under the Apache 2.0 license. See NOTICE.txt
for details.

Coverage.py kits no longer include tests and docs. If you were using them,
get in touch and let me know how.

Major new features:

Plugins: third parties can write plugins to add file support for non-Python
files, such as web application templating engines, or languages that compile
down to Python. See Plugins for how to use plugins, and
Plugin classes for details of how to write them. A plugin for measuring
Django template coverage is available: django_coverage_plugin

Gevent, eventlet, and greenlet are now supported. The [run]concurrency
setting, or the --concurrency command line switch, specifies the
concurrency library in use. Huge thanks to Peter Portante for initial
implementation, and to Joe Jevnik for the final insight that completed the
work.

The data storage has been re-written, using JSON instead of pickle. The
CoverageData class is a new supported API to the contents of the
data file. Data files from older versions of coverage.py can be converted to
the new format with python-mcoverage.pickle2json.

Wildly experimental: support for measuring processes started by the
multiprocessing module. To use, set --concurrency=multiprocessing,
either on the command line or in the .coveragerc file. Thanks, Eduardo
Schettino. Currently, this does not work on Windows.

New features:

Options are now also read from a setup.cfg file, if any. Sections are
prefixed with “coverage:”, so the [run] options will be read from the
[coverage:run] section of setup.cfg.

The HTML report now has filtering. Type text into the Filter box on the
index page, and only modules with that text in the name will be shown.
Thanks, Danny Allen.

A new option: coveragereport--skip-covered (or [report]skip_covered)
will reduce the number of files reported by skipping files with 100%
coverage. Thanks, Krystian Kichewko. This means that empty __init__.py
files will be skipped, since they are 100% covered.

You can now specify the --fail-under option in the .coveragerc file
as the [report]fail_under option.

The coveragecombine command now accepts any number of directories or
files as arguments, and will combine all the data from them. This means you
don’t have to copy the files to one directory before combining. Thanks,
Christine Lytwynec.

A new configuration option for the XML report: [xml]package_depth
controls which directories are identified as packages in the report.
Directories deeper than this depth are not reported as packages.
The default is that all directories are reported as packages.
Thanks, Lex Berezhny.

A new configuration option, [run]note, lets you set a note that will be
stored in the runs section of the data file. You can use this to
annotate the data file with any information you like.

The COVERAGE_DEBUG environment variable can be used to set the [run]debug
configuration option to control what internal operations are logged.

A new version identifier is available, coverage.version_info, a plain tuple
of values similar to sys.version_info.

Improvements:

Coverage.py now always adds the current directory to sys.path, so that
plugins can import files in the current directory.

Coverage.py now accepts a directory name for coveragerun and will run a
__main__.py found there, just like Python will. Thanks, Dmitry Trofimov.

The --debug switch can now be used on any command.

Reports now use file names with extensions. Previously, a report would
describe a/b/c.py as “a/b/c”. Now it is shown as “a/b/c.py”. This allows
for better support of non-Python files.

Missing branches in the HTML report now have a bit more information in the
right-hand annotations. Hopefully this will make their meaning clearer.

The XML report now contains a <source> element. Thanks Stan Hu.

The XML report now includes a missing-branches attribute. Thanks, Steve
Peak. This is not a part of the Cobertura DTD, so the XML report no longer
references the DTD.

The XML report now reports each directory as a package again. This was a bad
regression, I apologize.

In parallel mode, coverageerase will now delete all of the data files.

A new warning is possible, if a desired file isn’t measured because it was
imported before coverage.py was started.

The coverage.process_startup() function now will start coverage
measurement only once, no matter how many times it is called. This fixes
problems due to unusual virtualenv configurations.

Unrecognized configuration options will now print an error message and stop
coverage.py. This should help prevent configuration mistakes from passing
silently.

API changes:

The class defined in the coverage module is now called Coverage instead
of coverage, though the old name still works, for backward compatibility.

If the config_file argument to the Coverage constructor is specified as
”.coveragerc”, it is treated as if it were True. This means setup.cfg is
also examined, and a missing file is not considered an error.

Bug fixes:

The textual report and the HTML report used to report partial branches
differently for no good reason. Now the text report’s “missing branches”
column is a “partial branches” column so that both reports show the same
numbers. This closes issue 342.

The fail-under value is now rounded the same as reported results,
preventing paradoxical results, fixing issue 284.

Omitting files within a tree specified with the source option would
cause them to be incorrectly marked as unexecuted, as described in
issue 218. This is now fixed.

When specifying paths to alias together during data combining, you can now
specify relative paths, fixing issue 267.

Most file paths can now be specified with username expansion (~/src, or
~build/src, for example), and with environment variable expansion
(build/$BUILDNUM/src).

Trying to create an XML report with no files to report on, would cause a
ZeroDivideError, but no longer does, fixing issue 250.

When running a threaded program under the Python tracer, coverage.py no
longer issues a spurious warning about the trace function changing: “Trace
function changed, measurement is likely wrong: None.” This fixes
issue 164.

Static files necessary for HTML reports are found in system-installed places,
to ease OS-level packaging of coverage.py. Closes issue 259.

Source files with encoding declarations, but a blank first line, were not
decoded properly. Now they are. Thanks, Roger Hu.

The source kit now includes the __main__.py file in the root coverage
directory, fixing issue 255.

The report, html, and xml commands now accept a --fail-under
switch that indicates in the exit status whether the coverage percentage was
less than a particular value. Closes issue 139.

The reporting functions coverage.report(), coverage.html_report(), and
coverage.xml_report() now all return a float, the total percentage covered
measurement.

The HTML report’s title can now be set in the configuration file, with the
--title switch on the command line, or via the API.

Configuration files now support substitution of environment variables, using
syntax like ${WORD}. Closes issue 97.

Packaging:

The C extension is optionally compiled using a different more widely-used
technique, taking another stab at fixing issue 80 once and for all.

When installing, now in addition to creating a “coverage” command, two new
aliases are also installed. A “coverage2” or “coverage3” command will be
created, depending on whether you are installing in Python 2.x or 3.x.
A “coverage-X.Y” command will also be created corresponding to your specific
version of Python. Closes issue 111.

The coverage.py installer no longer tries to bootstrap setuptools or
Distribute. You must have one of them installed first, as issue 202
recommended.

Wildcards in include= and omit= arguments were not handled properly
in reporting functions, though they were when running. Now they are handled
uniformly, closing issue 143 and issue 163. NOTE: it is possible
that your configurations may now be incorrect. If you use include or
omit during reporting, whether on the command line, through the API, or
in a configuration file, please check carefully that you were not relying on
the old broken behavior.

Embarrassingly, the [xml] output= setting in the .coveragerc file simply
didn’t work. Now it does.

Combining data files would create entries for phantom files if used with
source and path aliases. It no longer does.

debugsys now shows the configuration file path that was read.

If an oddly-behaved package claims that code came from an empty-string
file name, coverage.py no longer associates it with the directory name,
fixing issue 221.

Coverage percentage metrics are now computed slightly differently under
branch coverage. This means that completely unexecuted files will now
correctly have 0% coverage, fixing issue 156. This also means that your
total coverage numbers will generally now be lower if you are measuring
branch coverage.

On Windows, files are now reported in their correct case, fixing issue 89
and issue 203.

If a file is missing during reporting, the path shown in the error message
is now correct, rather than an incorrect path in the current directory.
Fixes issue 60.

Running an HTML report in Python 3 in the same directory as an old Python 2
HTML report would fail with a UnicodeDecodeError. This issue (issue 193)
is now fixed.

Fixed yet another error trying to parse non-Python files as Python, this
time an IndentationError, closing issue 82 for the fourth time...

If coverage xml fails because there is no data to report, it used to
create a zero-length XML file. Now it doesn’t, fixing issue 210.

Running coverage.py under a debugger is unlikely to work, but it shouldn’t
fail with “TypeError: ‘NoneType’ object is not iterable”. Fixes
issue 201.

On some Linux distributions, when installed with the OS package manager,
coverage.py would report its own code as part of the results. Now it won’t,
fixing issue 214, though this will take some time to be repackaged by the
operating systems.

When coverage.py ended unsuccessfully, it may have reported odd errors like
'NoneType'objecthasnoattribute'isabs'. It no longer does,
so kiss issue 153 goodbye.

The HTML report has slightly tweaked controls: the buttons at the top of
the page are color-coded to the source lines they affect.

Custom CSS can be applied to the HTML report by specifying a CSS file as
the extra_css configuration value in the [html] section.

Source files with custom encodings declared in a comment at the top are now
properly handled during reporting on Python 2. Python 3 always handled them
properly. This fixes issue 157.

Backup files left behind by editors are no longer collected by the source=
option, fixing issue 168.

If a file doesn’t parse properly as Python, we don’t report it as an error
if the file name seems like maybe it wasn’t meant to be Python. This is a
pragmatic fix for issue 82.

The -m switch on coveragereport, which includes missing line numbers
in the summary report, can now be specified as show_missing in the
config file. Closes issue 173.

When running a module with coveragerun-m<modulename>, certain details
of the execution environment weren’t the same as for
python-m<modulename>. This had the unfortunate side-effect of making
coveragerun-munittestdiscover not work if you had tests in a
directory named “test”. This fixes issue 155.

Now the exit status of your product code is properly used as the process
status when running python-mcoveragerun.... Thanks, JT Olds.

When installing into pypy, we no longer attempt (and fail) to compile
the C tracer function, closing issue 166.

When combining data files from parallel runs, you can now instruct
coverage.py about which directories are equivalent on different machines. A
[paths] section in the configuration file lists paths that are to be
considered equivalent. Finishes issue 17.

The number of partial branches reported on the HTML summary page was
different than the number reported on the individual file pages. This is
now fixed.

An explicit include directive to measure files in the Python installation
wouldn’t work because of the standard library exclusion. Now the include
directive takes precedence, and the files will be measured. Fixes
issue 138.

In order to help the core developers measure the test coverage of the
standard library, Brandon Rhodes devised an aggressive hack to trick Python
into running some coverage.py code before anything else in the process.
See the coverage/fullcoverage directory if you are interested.

The HTML report now has hotkeys. Try n, s, m, x, b,
p, and c on the overview page to change the column sorting.
On a file page, r, m, x, and p toggle the run, missing,
excluded, and partial line markings. You can navigate the highlighted
sections of code by using the j and k keys for next and previous.
The 1 (one) key jumps to the first highlighted section in the file,
and 0 (zero) scrolls to the top of the file.

HTML reporting is now incremental: a record is kept of the data that
produced the HTML reports, and only files whose data has changed will
be generated. This should make most HTML reporting faster.

Running Python files

Modules can now be run directly using coveragerun-mmodulename, to
mirror Python’s -m flag. Closes issue 95, thanks, Brandon Rhodes.

coveragerun didn’t emulate Python accurately in one detail: the
current directory inserted into sys.path was relative rather than
absolute. This is now fixed.

Pathological code execution could disable the trace function behind our
backs, leading to incorrect code measurement. Now if this happens,
coverage.py will issue a warning, at least alerting you to the problem.
Closes issue 93. Thanks to Marius Gedminas for the idea.

The C-based trace function now behaves properly when saved and restored
with sys.gettrace() and sys.settrace(). This fixes issue 125
and issue 123. Thanks, Devin Jeanpierre.

Coverage.py can now be run directly from a working tree by specifying
the directory name to python: pythoncoverage_py_working_dirrun....
Thanks, Brett Cannon.

A little bit of Jython support: coverage run can now measure Jython
execution by adapting when $py.class files are traced. Thanks, Adi Roiban.

Reporting

Partial branch warnings can now be pragma’d away. The configuration option
partial_branches is a list of regular expressions. Lines matching any of
those expressions will never be marked as a partial branch. In addition,
there’s a built-in list of regular expressions marking statements which should
never be marked as partial. This list includes whileTrue:, while1:,
if1:, and if0:.

The --omit and --include switches now interpret their values more
usefully. If the value starts with a wildcard character, it is used as-is.
If it does not, it is interpreted relative to the current directory.
Closes issue 121.

Syntax errors in supposed Python files can now be ignored during reporting
with the -i switch just like other source errors. Closes issue 115.

BACKWARD INCOMPATIBILITY: the --omit and --include switches now take
file patterns rather than file prefixes, closing issue 34 and issue 36.

BACKWARD INCOMPATIBILITY: the omit_prefixes argument is gone throughout
coverage.py, replaced with omit, a list of file name patterns suitable for
fnmatch. A parallel argument include controls what files are included.

The run command now has a --source switch, a list of directories or
module names. If provided, coverage.py will only measure execution in those
source files. The run command also now supports --include and --omit
to control what modules it measures. This can speed execution and reduce the
amount of data during reporting. Thanks Zooko.

The reporting commands (report, annotate, html, and xml) now have an
--include switch to restrict reporting to modules matching those file
patterns, similar to the existing --omit switch. Thanks, Zooko.

Reporting:

Completely unexecuted files can now be included in coverage results, reported
as 0% covered. This only happens if the –source option is specified, since
coverage.py needs guidance about where to look for source files.

Python files with no statements, for example, empty __init__.py files,
are now reported as having zero statements instead of one. Fixes issue 1.

Reports now have a column of missed line counts rather than executed line
counts, since developers should focus on reducing the missed lines to zero,
rather than increasing the executed lines to varying targets. Once
suggested, this seemed blindingly obvious.

Coverage percentages are now displayed uniformly across reporting methods.
Previously, different reports could round percentages differently. Also,
percentages are only reported as 0% or 100% if they are truly 0 or 100, and
are rounded otherwise. Fixes issue 41 and issue 70.

The XML report output now properly includes a percentage for branch coverage,
fixing issue 65 and issue 81, and the report is sorted by package
name, fixing issue 88.

The precision of reported coverage percentages can be set with the
[report]precision config file setting. Completes issue 16.

Line numbers in HTML source pages are clickable, linking directly to that
line, which is highlighted on arrival. Added a link back to the index page
at the bottom of each HTML page.

Execution and measurement:

Various warnings are printed to stderr for problems encountered during data
measurement: if a --source module has no Python source to measure, or is
never encountered at all, or if no data is collected.

Doctest text files are no longer recorded in the coverage data, since they
can’t be reported anyway. Fixes issue 52 and issue 61.

Threads derived from threading.Thread with an overridden run method
would report no coverage for the run method. This is now fixed, closing
issue 85.

Programs that exited with sys.exit() with no argument weren’t handled
properly, producing a coverage.py stack trace. This is now fixed.

Programs that call os.fork will properly collect data from both the child
and parent processes. Use coveragerun-p to get two data files that can
be combined with coveragecombine. Fixes issue 56.

When measuring code running in a virtualenv, most of the system library was
being measured when it shouldn’t have been. This is now fixed.

Coverage.py can now be run as a module: python-mcoverage. Thanks,
Brett Cannon.

Settings are now read from a .coveragerc file. A specific file can be
specified on the command line with --rcfile=FILE. The name of the file
can be programmatically set with the config_file argument to the
coverage() constructor, or reading a config file can be disabled with
config_file=False.

Parallel data file names now have a random number appended to them in
addition to the machine name and process id. Also, parallel data files
combined with coveragecombine are deleted after they’re combined, to
clean up unneeded files. Fixes issue 40.

Exceptions thrown from product code run with coveragerun are now
displayed without internal coverage.py frames, so the output is the same as
when the code is run without coverage.py.

Branch coverage: coverage.py can tell you which branches didn’t have both (or
all) choices executed, even where the choice doesn’t affect which lines were
executed. See Branch coverage measurement for more details.

The table of contents in the HTML report is now sortable: click the headers
on any column. The sorting is persisted so that subsequent reports are
sorted as you wish. Thanks, Chris Adams.

Coverage.py has a new command line syntax with sub-commands. This expands
the possibilities for adding features and options in the future. The old
syntax is still supported. Try coveragehelp to see the new commands.
Thanks to Ben Finney for early help.

Coverage.py is now a package rather than a module. Functionality has been
split into classes.

HTML reports and annotation of source files: use the new -b (browser)
switch. Thanks to George Song for code, inspiration and guidance.

The trace function is implemented in C for speed. Coverage.py runs are now
much faster. Thanks to David Christian for productive micro-sprints and
other encouragement.

The minimum supported Python version is 2.3.

When using the object API (that is, constructing a coverage() object), data
is no longer saved automatically on process exit. You can re-enable it with
the auto_data=True parameter on the coverage() constructor.
The module-level interface still uses automatic saving.

Code in the Python standard library is not measured by default. If you need
to measure standard library code, use the -L command-line switch during
execution, or the cover_pylib=True argument to the coverage()
constructor.

API changes:

Added parameters to coverage.__init__ for options that had been set on
the coverage object itself.

Added clear_exclude() and get_exclude_list() methods for programmatic
manipulation of the exclude regexes.

Added coverage.load() to read previously-saved data from the data file.